Antenna system using variable phase pattern synthesis

ABSTRACT

Disclosed is an antenna system for radiating wave energy in a radiation pattern having a desired shape. Pattern shaping is achieved by synthesizing the desired pattern using component antenna beams. A composite aperture excitation is developed which is substantially the superposition of component aperture excitations corresponding to the component antenna beams, and wherein the component aperture excitations have predetermined average phase displacements from each other to reduce reinforcement of excitation amplitude in the composite aperture excitation.

United States Patent 11 1 Giannini ANTENNA SYSTEM USING VARIABLE PHASE PATTERN SYNTHESIS [75] Inventor: R. J. Giannini, Setauket, N.Y.

[73] Assignee: Hazeltine Corporation, Greenlawn,

22 Filed: May 25,1973

21 Appl. No.: 364,182

52 11.5.0. 343/771; 343/844; 343/853 [51] Int. Cl. ..I-I0lq 13/10 [58] FieldofSearch 343/771,778, 853, 854, 343/844 [5 6] References Cited UNITED STATES PATENTS 2,730,7i7 l/l956 Katchky etal ..343/77l 2,878,472 3/1959 Stems 343/853 2,981,944 4/1961 Washburne ..343/771 3,182,325 4/1965 Blume ..343/s54 I20 ll 15 I30 Bl) |2b I/lOb IOc l/|Od I *i/IOE -|/lOf [3h lOh l5 |2h INPUT SIDE VIEW 1451 Sept. 2, 1975 3,258,774 6/1966 Kinsey 343/854 3,259,902 7/1966 Malech 343/854 3,526,898 9/1970 Plunk et a] 343/854 3,604,010 9/1971 Schwartz et a]. 343/768 Primary Examiner-Eli Lieberman ABSTRACT 7 Claims, 11 Drawing Figures FRONT VIEW PATENTED 975 SHEET 1 BF 5 lOh FRONT VIEW SIDE VIEW FIG. lb

FIG.

PAIENIED 2W5 3.903.524

SIIEEI 2 [IF 5 T VOLTAGE b ANGLE (A) FIG. 20

0 ANGLE (A) FIG. 2b

VOLTAGE ANGLE (A) FIG. 20

PATENTED 2 975 PHASE SHEET 3 [1F 5 PRIOR ART I00 lOb 10 lOd lOe lf I6 lOh ELEMENT FIG. 30

PRIOR ART VOLTAGE 4 I00 lOb IOC 10d I09 lOf lOg lOh ELEMENT FIG. 3b

PATENTED 2|975 3, 903 524 snmunis lOcl lOb lOc lOd lOe lOf lOg lOh ELEMENTS FIG. 40

VOLTAGE I00 lOb IOc lOd le ldf lO g \dh ELEMENTS FIG. 4b

PATENTEDSEP 21% 3,903,524

sumsnrg & 1 201 l 1 LT! INPUT FRONT VIEW SIDE VIEW FIG. 50 FIG. 5b

ANTENNA SYSTEM USING VARIABLE PHASE PATTERN SYNTHESIS BACKGROUND OF THE INVENTION This invention relates to antenna systems for radiating wave energy in a desired pattern of radiation amplitude. In particular this invention relates to antennas designed using the pattern synthesis technique to determine the amplitude and phase of the aperture excitation which will achieve the desired rediation amplitude pattern.

It is well known that any desired radiation amplitude pattern may be approximately achieved using a combination of component antenna beams which result from component aperture excitations. The desired amplitude pattern results from the superposition of the component beams in space, and a corresponding composite aperture excitation is determined by the superposition of the component aperture excitations.

In practice it is convenient to choose component aperture excitations which radiate an orthogonal set of component antenna beams. In an orthogonal set of antenna beams, each beam has a direction of maximum radiation associated with it, in which direction all other beams in the orthogonal set have a radiation null. Using an orthogonal set of component antenna beams results in there being a corresponding set of directions in space at each of which the amplitude of radiation is determined by the amplitude ofa single component aperture excitation.

The pattern synthesis technique may be used to determine an aperture excitation which will cause the antenna to radiate an antenna pattern having any desired amplitude characteristic with direction. As generally applied, the pattern synthesis technique results in one area of the antenna aperture having all of the excitations in phase. The result is that in this area of the antenna aperture there is a substantial reinforcement of the component electromagnetic fields, which can result in difficulties associated with high-power density. Another disadvantage occurs when the antenna aperture is an array of antenna elements because the elements in the area of phase reinforcement of the orthogonal excitations must have a substantially larger amount of energy coupled to them than is coupled to the other elements in the array. This large amount of coupling creates substantial difficulty when a series feed arrangement is used to couple wave energy to the elements of the array.

OBJECTS OF THE INVENTION It is, therefore, an object of the present invention to provide a new and improved antenna system for radiating wave energy in a desired radiation pattern using a composite aperture excitation which is the superposition of a plurality of component aperture excitations.

It is a further object of the present invention to provide such an antenna system wherein the aperture does not have an area where there is substantial phase reinforcement of the component aperture excitations.

It is a still further object of the present invention to porvide such an antenna system using an array of antenna elements wherein the amplitude of the wave energy coupled to the elements has a more uniform distribution among the elements than could have been achieved using prior art aperture excitations.

In accordance with the present invention, there is provided an antenna system for radiating wave energy in a desired radiation pattern. The antenna system includes an aperture, comprising an array of antenna elements, for radiated wave energy patterns in response to wave energy excitations. The antenna system additionally includes means for supplying wave energy to the elements with predetermined relative phases and amplitudes to develop a composite wave energy excitation on the aperture. The relative phase and amplitude of the wave energy supplied to each of the elements comprises the vector sum of a plurality of component aperture excitations, measured at the location of the element on the aperture, including a reference excitation and other component excitations having both positive and negative phase variation on the aperture with respect to the reference excitation. The component excitations with positive phase variation have, with respect to the reference excitation, an average phase displacement which is a first monotonic function of the phase variation, and the component excitations with negative phase variation have, with respect to the reference excitation, an average phase displacement which is a second monotonic function of the phase variation. All excitations have the same sense of average phase displacement. There results a set of element excitations without substantial amplitude reinforcement of the component excitations at any selected one of the antenna elements.

For a better understanding of the present invention, together with other and further objects thereof, reference is bad to the following description taken in con junction with the accompanying drawings and its scope will be pointed out in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1(a) and 1(b) illustrate respectively the side view and front view of a linear array antenna system constructed in accordance with the present invention. FIGS. 2(a), and 2(b) and 2(c) illustrate a pattern synthesis technique.

FIGS. 3(a) and 3(b) illustrate respectively the component and composite aperture excitations used in the prior art aperture synthesis technique.

FIGS. 4(a) and 4(b) illustrate respectively the component and composite aperture excitations used in the aperture synthesis technique in accordance with the present invention.

FIGS. 5(a) and 5(b) illustrate respectively the front view and side view of another antenna system constructed in accordance with the present invention.

DESCRIPTION AND OPERATION OF THE FIGURE 1 ANTENNA SYSTEM The antenna system illustrated in FIG. 1 includes a linear array of dipoles 10(a) through 10(11), mounted on a conductive ground plane 11. Transmission lines 12(a) through 12(11) connect the dipoles 10 to corresponding directional couplers 13(a) through 1311). The directional couplers 13 are in series and are connected to a common input port by transmission line 14. Resistive loads 15 are used to terminate the transmission line 14 and the isolated outputs of the couplers 13.

The dipoles 10, mounted on the ground plane ll, form an antenna aperture which will radiate wave energy patterns in response to wave energy excitations on the aperture. A wave energy excitation is developed on the aperture by supplying to the individual dipoles wave energy signals having preselected relative amplitudes and phases.

The spacing of the dipoles 10 along the linear array, the length of the linear array, and the number of dipoles 10 required are chosen in accordance with principles which are familiar to those skilled in the art. It will be evident that other antenna elements besides dipoles may be used to construct the linear array of the FIG. 1 embodiment. Other commonly used antenna elements are feedhorns, waveguide slots and spirals.

In the FIG. 1 antenna, wave energy signals are supplied to the dipoles 10 from the input by means of transmission line 14, directional couplers 13 and trans mission lines 12(a) through 12(11). It will be evident to one skilled in the art that the amplitude of the wave en ergy signals coupled to each of the dipoles 10 is regulated by the coupling coefficients of the various directional couplers 13(a) through 13(11). The phase of the wave energy signals coupled to each of the dipoles 10 is determined by the phase length of the input transmission line 14, the directional couplers I3 and the transmission lines 12. It is evident that the structure provides for individual adjustment of the amplitude and phase of wave energy signals that are simultaneously coupled to each of the dipoles 10. The transmission line 14 used in the FIG. I embodiment may be of any type appropriate for use at the operating frequency of the antenna. Typical transmission lines which might be used are waveguides, coaxial lines, and strip transmission lines. The directional couplers 13 may be any type appropriate to the chosen transmission line type. Those skilled in the art will recognize that other means, besides directional couplers, may be used to supply wave energy signals to the dipoles 10 from the input. Examples are reactive power dividers or enclosed multi-mode transmission lines.

FIG. 2(a) indicates a wave energy pattern which may be desired from the FIG. 1 antenna. The amplitude of the wave energy in the desired pattern is constant over a particular range of the angle (A), which is designated in the FIG. 1 drawing. It is also desired that there be no radiation at angles outside of the desired angular region.

FIG. 2(b) indicates the main lobes of a set of component orthogonal antenna beams which would be radiated by the FIG. 1 antenna when fed with a set of wave energy signals whose amplitude and phases are chosen in accordance with prior art techniques. The component beams 16(0) through 16(6) would be radiated by component aperture excitations having uniform amplitude at all of the elements and phase distributions which are orthogonal to each other. Orthogonal phase distributions have a phase variation relative to each other which is an integral multiple of 277' across the aperture of the antenna.

In FIG. 2(1)) the beam designated 16(0) is a beam which would be radiated by a reference component excitation having equal amplitude and equal phase at all of the elements. Beams designated 16(1)) and 16((1) are radiated by other component aperture excitations with phase variations, with respect to the beam 16(c) excitation, of plus ZTr and minus 211', respectively. Beams designated 16((1) and 16(6) are radiated by component excitations which have phase variations of plus 471' and minus 411', respectively, with respect to the reference excitation corresponding to beam 16(c).

FIG. 2(0) represents the composite radiation pattern which results from the superposition of the five beams in FIG. 2(b). This radiation pattern is achieved if the aperture is provided with a composite aperture excitation having an amplitude and phase distribution which is the superposition of the component aperture excitations which result in the beams of FIG. 2(b).

In order to develop the desired composite radiation pattern shown in FIG. 2c from the linear array of FIG. 1 using prior art techniques, such as those described in detail in Section 2.13 of the Antenna Engineering Handbook by Henry .lasik (McGraw-Hill, 1961), it is necessary to use an aperture excitation which is the superposition of the composite aperture excitations corresponding to the component antenna beams of FIG. 2b. In the illustrated example all of the component antenna beams have the same amplitude, so it would be appropriate that all of the component aperture excitations have the same amplitude. The phase distributions 17(a) through 17(e) of the component aperture excitations which result in the component antenna beams 16(11) through 16((e) of FIG. 2b are illustrated in FIG. 3a. In order to obtain the required phase and amplitude excitations for elements 10(a) through 10(11) it is necessary to make a vector addition of the component aperture excitations at the location on the aperture of each of the antenna elements 10(a) through 10(11). Since all of the component excitations have uniform amplitude distribution on the aperture, and each has the same amplitude, the amplitude and phase of the required excitation at each element is determined by vector addition of five vectors (one for each component aperture excitation) of equal amplitude and each having a phase which is determined by the phase distributions shown in FIG. 3a.

For example, in accordance with prior art techniques, the excitation for element 10(a) is determined by adding five vectors having equal amplitude and phases of approximately 21r, 1r, 0, 1r and 2'rr. These phases are determined by the value of phase distributions 17((1) through 17(2) at the location of element 10(a) on the aperture. Likewise, for example, the excitation for element 10((1) is determined by adding five vectors having equal amplitude and approximately zero phase as indicated by FIG. 3a.

FIG. 3(b) shows the resultant amplitudes of excitation for each of the elements 10(a) through 10(11). It will be noted that the amplitudes of excitation for elements 10((1) and 10(2) are greatly in excess of the average amplitude excitation of the elements.

Having determined the amplitude and phase of the excitation required for each of the elements 10(a) through 10(11) of the FIG. 1 array, the desired excitation may be achieved by proper selection of the coupling values for couplers 13(0) through 13(11) and transmission lines 12((1) through 12(lz). To achieve this it is necessary to compute the percentage of the total power supplied to all of the antenna elements which must be supplied to each of the individual elements. The coupling value for each of couplers 13(a) through 13(11) is then computed on the basis of the fractional power to be supplied to each element with respect to the power remaining in transmission line 14 at the input to the particular coupler, allowing for power previously coupled out. According to the type of transmission line used it may also be necessary to make allowance for power loss in the transmission line 14. The phase of the wave energy supplied to each of the elements ((1) through 10(11) is adjusted by varying the length of the respective transmission lines 12(0) through 12(12). Illustrated in FIG. 3b is the amplitude excitation which would result for each of the elements 10(u) through 10(11) if the prior art synthesis technique were used to achieve the composite radiation pattern illustrated in FIG. 20. As is evident from FIG. 3b and has been discussed above, the phase variations of the prior art synthesis technique tend to cause reinforcement of the amplitude of the excitations of the elements in a particular region of the aperture. In the set of amplitude excitations illustrated in FIG. 3b elements 10(d) and 10(e) have a much greater amplitude excitation than the remaining elements. In the illustrated case the differences in amplitude excitations can be as much as 10:] in voltage, which results in differences of 100:1 in the power to be supplied to the elements of the array.

DESCRIPTION AND OPERATION OF THE ANTENNA SYSTEM OF FIG. 1 BASED ON THE PRESENT INVENTION It is an object of the present invention to provide an antenna for radiating a desired radiation pattern without substantial reinforcement of the excitation at any of the elements on the aperture. An antenna constructed in accordance with the present invention may be identical in circuit arrangement and detailed design technique to prior art antennas but different component values are used to achieve the required amplitude and phase excitations for the elements. The present invention avoids the disadvantage of the prior art aperture designs which result in substantial reinforcement of the energy supplied to particular elements of the array.

FIG. 4(a) indicates the phase distributions 17(a) through l7'(e) of component aperture excitations which are selected in accordance with the present invention. It should be noted that there is a reference ex citation l7(c) and other component excitations having both positive and negative phase variation with respect to the reference excitation. It should be further noted that the component excitations 17'(a) and l7(b) which have positive phase variation also have, with respect to the reference excitation l7'(c), average phase displacements x and x, respectively, and these average phase displacements x and x are monotonically related to the phase variation of their respective component excitations 17'(a) and 17'(b). Thus, component excitation l7'(a), which has a phase variation of 4w with respect to the reference excitation 17(c), has a greater average phase displacement .t' than component excitation 17(b), which has a phase variation of 211' and an average phase displacement x. Similarly, component excitations l7'(d) and l7(e), which have negative phase variation. also have, with respect to the reference excitation 17'(c), average phase displacements x and x, respectively, and these average phase displacements and x are monotonically related to the phase variation of their respective component excitations l7'(d) and l7(e). The average phase displacements of all excitations with respect to the reference excitation have the same sense. Use of displacements with the same sense prevents phase reinforcement of the component excitations at another point on the aperture.

In the embodiment described by the FIG. 4(a) phase diagram, excitation l7(a) has the same average phase displacement x as excitation 17'(e). Similarly, excitation l7'(b) has the same average phase displacement x as excitation 17'(d). It should be noted that the average phase displacements of excitations having a positive phase variation may be a different monotonic function of the phase variation than the average phase displacements of excitations having a negative phase variation.

The effect of introducing average phase displacement of the component aperture excitations is to eliminate the point of phase reinforcement in the composite excitation. FIG. 4(b) illustrates the amplitude of the composite excitation at the various array elements 10(a) to 10(e) of FIG. 1, which results from the super position of the component excitations 17'(a) through 17(e). By comparing FIGS. 3(b) and 4(b), it will be seen that the relative amplitude of excitation for the elements 10(d) and 10(6) has been reduced by approximately 60 percent. The amplitudes of excitation which must be coupled to the remaining elements of the array have been correspondingly increased, resulting in a more uniform amplitude distribution in the composite aperture excitation. The actual amplitude and phase excitations for an antenna array design in accordance with the present invention is determined in a manner similar to that for the prior art excitation, except that component aperture excitations having phase displacements similar to that illustrated in FIG. 4a are used to determine the amplitude and phase excitations for the various elements in the array.

The effect of the average phase displacement of the component aperture excitations is a corresponding phase change in the component radiated beams. Therefore, if the component excitations of FIG. 4(a) are used, antenna beam 16(b) of FIG. 2(12) will result from excitation l7(b) of FIG. 4(a). The component antenna beam 16(b) will have a phase difference from the reference component antenna beam 16(0) equal to the average phase displacement x of the component excitation l7(b). The effect of the phase differences among antenna beams on the composite antenna pattern is small, since the phase difference between adjacent antenna beams is small. In the FIG. 4(a) embodiment adjacent beams are displaced in phase by approximately 1'r/2. This phase difference between adjacent beams may cause an increase in the ripple effect on the composite antenna pattern as shown in FIG. 2(c). The magni tude of the ripple effect increases with increased phase difference between adjacent beams.

The desired shape of the radiation pattern may be other than uniform amplitude as in the FIG. 2 example. Specific applications may require radiation patterns which are tapered or even multi-Iobed. In such case, the desired pattern may be synthesized using compo nent excitations with different relative amplitudes. In some cases component excitations may even have opposite polarity. However. the present invention may be applied to these cases without difficulty.

It will be evident to those skilled in the art that finer pattern detail and more precise correspondence between the composite antenna pattern and the desired antenna pattern will result from the use of a larger antenna aperture with correspondingly smaller compo nent antenna beams. The selection of aperture size would naturally involve a tradeoff between the lower cost of a small aperture and the better correspondence to the desired pattern available from a large aperture.

It will be evident to one skilled in the art that using the basic principles of the invention, as they are disclosed above, one can use the present invention to construct antenna systems of many different forms. For example, the linear array of the FIG. 1 embodiment may be combined with other linear arrays to form a planar or cylindrical array antenna using the present invention. The technique for formulating the composite aperture excitation may also be applied in the perpendicular plane of an antenna system which uses a plurality of the FIG. 1 linear arrays. It will also be evident that it is not necessary that the antenna aperture be an array of elements. Once a desired composite aperture excitation has been formulated using the synthesis technique, it is possible to achieve that illumination on an aperture consisting of a transmissive or reflective focusing means excited by conventional means, such as a plurality of feed elements. In such an application, each feed element forms a component excitation on the focusing means and a composite excitation on the aperture would result from simultaneous excitation of all of the feed elements.

DESCRIPTION OF THE FIG. 5 ANTENNA SYSTEM FIG. 5 illustrates another linear array antenna system constructed in accordance with the present invention. In the FIG. 5 antenna system the antenna elements consist of slot elements located in a side wall of a rectangular waveguide 19. In this embodiment the amplitude of the wave energy supplied to each of the slot elements 20 is determined by the fraction of the wave energy in the waveguide coupled to the slot element 20, which is a function of the angle of the slot element 20 in the side wall of the waveguide 19. The phase of the wave energy coupled to each of the slot elements 20 is determined by the phase of the wave energy in the wave guide 19 at the location of the slot element 20. The phase of any slot element 20 may be changed by 180 by reversing the slot inclination angle. Once a desired composite aperture excitation, amplitude and phase has been determined with the invention as described above, it is possible to locate the slot elements 20 along the waveguide 19 so that wave energy signals introduced at the input end of the waveguide 19 are coupled to the slot elements 20 with the required phase; the inclination angle of each slot element 20 is adjusted so that the slot elements 20 will have the required amplitude of wave energy signals coupled to them.

The present invention is particularly advantageous in the FIG. 5 embodiment since there is a practical limit to the fraction of the energy in the waveguide 19 which I may be coupled to each slot element 20. The present invention facilitates the implementation of the FIG. 5 embodiment by allowing the use of an aperture excitation which has a more uniform amplitude distribution of the wave energy signals coupled to each of the elements.

In describing the various embodiments above, reference has been made to transmitting antenna systems, but it will be recognized by those skilled in the art that the principles of the present invention can also be applied to receiving antenna systems. Accordingly, the appended claims are intended to be construed as covering both transmitting and receiving antenna systems regardless of the descriptive terms actually used therein.

While there have been described what are at present considered to be the preferred embodiments of this invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention and it is, therefore. aimed to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What is claimed is:

1. An antenna system for radiating wave energy in a desired radiation pattern comprising:

an aperture comprising an array of antenna elements for radiating wave energy patterns in response to wave energy excitations;

means for supplying wave energy to said elements with pre-determined relative phases and amplitudes to develop a composite wave energy excitation on said aperture, the relative phase and amplitude of the wave energy supplied to each of said elements comprising the vector sum of a plurality of component aperture excitations, measured at the location of said element on said aperture, including a reference excitation and other component excitations having both positive and negative phase variation on said aperture with respect to said reference excitation, said component excitations with positive phase variation having with respect to said reference excitation an average phase displacement which is a first monotonic function of said phase variation, and said component excitations with negative phase variation having, with respect to said reference excitation, an average phase displacement which is a second monotonic function of said phase variation, all excitations having the same sense of average phase displacement, thereby resulting in a set of element excitations without substantial amplitude reinforcement of said component excitations at any selected one of said antenna elements.

2. An antenna system for radiating wave energy in a desired radiation pattern comprising:

an aperture comprising a linear array of antenna elements for radiating wave energy patterns in response to wave energy excitations;

means for supplying wave energy to said elements with predetermined relative phases and amplitudes to develop a composite wave energy excitation on said aperture, the relative phase and amplitude of the wave energy supplied to each of said elements comprising the vector sum of a plurality of component aperture excitations, measured at the location of said element on said aperture, including a reference excitation and other component excitations having both positive and negative phase variation on said aperture with respect to said reference excitation, said component excitations with positive phase variation having with respect to said reference excitation an average phase displacement which is a first monotonic function of said phase variation, and said component excitations with negative phase variation having, with respect to said reference excitation, an average phase dis placement which is a second monotonic function of said phase variation, all excitations having the same sense of average phase displacement, thereby resulting in a set of element excitations without substantial amplitude reinforcement of said component excitations at any selected one of said antenna elements.

3. An antenna system for radiating wave energy in a desired radiation pattern comprising:

an aperture comprising an array of antenna elements for radiating wave energy patterns in response to wave energy excitations;

means for supplying wave energy to said elements with predetermined relative phases and amplitudes to develop a composite wave energy excitation on said aperture, the relative phase and amplitude of the wave energy supplied to each of said elements comprising the vector sum of a plurality of uniform amplitude, orthogonal-phase component aperture excitations, measured at the location of said elements on said aperture, including a reference excitation and other component excitations having both positive and negative phase variation on said aperture with respect to said reference excitation, said component excitations with positive phase variation having with respect to said reference excitation an average phase displacement which is a first monotonic function of said phase variation, and said component excitations with negative phase variation having, with respect to said reference excitation, an average phase displacement which is a second monotonic function of said phase variation, all excitations having the same sense of average phase displacement, thereby resulting in a set of element excitations without substantial amplitude reinforcement of said component excitations at any selected one of said antenna elements.

4. An antenna system for radiating wave energy signals in a desired radiation pattern, comprising a waveguide having an aperture comprising a linear array of slots for radiating wave energy patterns in response to wave energy excitations and having selected slot orien tations and locations which cause wave energy supplied to one end of said waveguide to develop a composite wave energy excitation on said aperture wherein the wave energy supplied to each of said slots has a relative phase and amplitude comprising the vector sum of a plurality of component aperture excitations, measured at the location of said slot in said array, including a reference component excitation and other component excitations having both positive and negative phase variation along said linear array with respect to said reference excitation, said component excitations with positive phase variation having with respect to said reference excitation an average phase displacement which is a first monotonic function of said phase variation, and said component excitations with negative phase variation having with respect to said reference excitation an average phase displacement which is a second monotonic function of said phase variation, all excitations having the same sense of average phase displacement, thereby resulting in a composite wave energy excitation without substantial amplitude reinforcement of said component excitations at any of said slots in said waveguide.

5. An antenna system for radiating wave energy signals in a desired radiation pattern, comprising a waveguide having an aperture comprising a linear array of slots formed into one of the narrow walls of said waveguide for radiating wave energy patterns in response to wave energy excitation and having selected slot orien tations and locations which cause wave energy supplied to one end of said waveguide to develop a composite wave energy excitation on said aperture wherein the wave energy supplied each of said slots has a relative phase and amplitude comprising the vector sum of a plurality of component aperture excitations, measured at the location of said slot in said array, including 21 reference component excitation and other component excitations having both positive and negative phase variations along said linear array with respect to said reference excitation, said component excitations with positive phase variation having with respect to said reference excitation an average phase displacement which is a first monotonic function of said phase variation, and said component excitations with negative phase variation having with respect to said reference excitation an average phase displacement which is a second monotonic function of said phase variation, all excitations having the same sense of average phase displacement, thereby resulting in a composite wave energy excitation without substantial amplitude reinforcement of said component excitations at any of said slots in said waveguide.

6. An antenna system for radiating wave energy signals in a desired radiation pattern, comprising a waveguide having an aperature comprising a linear array of slots for radiating wave energy patterns in response to wave energy excitations and having selected slot orientations and locations which cause wave energy supplied to one end of said waveguide to develop a composite wave energy excitation on said aperature wherein the wave energy supplied each of said slots has a relative phase and amplitude comprising the vector sum of a plurality of uniform amplitude, orthogonalphase component aperature excitations, measured at the location of said slot in said array, including a reference component excitation and other component excitations having both positive and negative phase variation along said linear array with respect to said reference excitation, said component excitations with positive phase variation having with respect to said reference excitation an average phase displacement which is a first monotonic function of said phase variation, and said component excitations with negative phase variation having with respect to said reference excitation an average phase displacement which is a second monotonic function of said phase variation, all excitations having the same sense of average phase displacement, thereby resulting in a composite wave energy excitation without substantial amplitude reinforcement of said component excitations at any of said slots in said waveguide.

7. An antenna system for radiating wave energy in a desired radiation pattern, comprising a rectangular waveguide, having an aperture comprising a linear array of slots for radiating wave energy patterns in response to wave energy excitations, said slots being formed into one of the narrow walls of said waveguide and having selected slot orientations and locations which cause wave energy supplied to one end of said waveguide to develop a composite wave energy excitation on said aperture wherein the wave energy supplied to each of said slots has a relative phase and amplitude comprising the vector sum of a plurality of uniformamplitude, orthogonal-phase component aperture excitations, if measured at the location of said slot in said array, including a reference component excitation and other component excitations having both positive and negative phase variation along said linear array with reis a second monotonic function of said phase variation, all excitations having the same sense of average phase displacement; thereby resulting in a composite wave energy excitation without substantial amplitude reinforcement of said component excitations at any of said slots in said waveguide. 

1. An antenna system for radiating wave energy in a desired radiation pattern comprising: an aperture comprising an array of antenna elements for radiating wave energy patterns in response to wave energy excitations; means for supplying wave energy to said elements with predetermined relative phases and amplitudes to develop a composite wave energy excitation on said aperture, the relative phase and amplitude of the wave energy supplied to each of said elements comprising the vector sum of a plurality of component aperture excitations, measured at the location of said element on said aperture, including a reference excitation and other component excitations having both positive and negative phase variation on said aperture with respect to said reference excitation, said component excitations with positive phase variation having with respect to said reference excitation an average phase displacement which is a first monotonic function of said phase variation, and said component excitations with negative phase variation having, with respect to said reference excitation, an average phase displacement which is a second monotonic function of said phase variation, all excitations having the same sense of average phase displacement, thereby resulting in a set of element excitations without substantial amplitude reinforcement of said component excitations at any selected one of said antenna elements.
 2. An antenna system for radiating wave energy in a desired radiation pattern comprising: an aperture compRising a linear array of antenna elements for radiating wave energy patterns in response to wave energy excitations; means for supplying wave energy to said elements with predetermined relative phases and amplitudes to develop a composite wave energy excitation on said aperture, the relative phase and amplitude of the wave energy supplied to each of said elements comprising the vector sum of a plurality of component aperture excitations, measured at the location of said element on said aperture, including a reference excitation and other component excitations having both positive and negative phase variation on said aperture with respect to said reference excitation, said component excitations with positive phase variation having with respect to said reference excitation an average phase displacement which is a first monotonic function of said phase variation, and said component excitations with negative phase variation having, with respect to said reference excitation, an average phase displacement which is a second monotonic function of said phase variation, all excitations having the same sense of average phase displacement, thereby resulting in a set of element excitations without substantial amplitude reinforcement of said component excitations at any selected one of said antenna elements.
 3. An antenna system for radiating wave energy in a desired radiation pattern comprising: an aperture comprising an array of antenna elements for radiating wave energy patterns in response to wave energy excitations; means for supplying wave energy to said elements with predetermined relative phases and amplitudes to develop a composite wave energy excitation on said aperture, the relative phase and amplitude of the wave energy supplied to each of said elements comprising the vector sum of a plurality of uniform amplitude, orthogonal-phase component aperture excitations, measured at the location of said elements on said aperture, including a reference excitation and other component excitations having both positive and negative phase variation on said aperture with respect to said reference excitation, said component excitations with positive phase variation having with respect to said reference excitation an average phase displacement which is a first monotonic function of said phase variation, and said component excitations with negative phase variation having, with respect to said reference excitation, an average phase displacement which is a second monotonic function of said phase variation, all excitations having the same sense of average phase displacement, thereby resulting in a set of element excitations without substantial amplitude reinforcement of said component excitations at any selected one of said antenna elements.
 4. An antenna system for radiating wave energy signals in a desired radiation pattern, comprising a waveguide having an aperture comprising a linear array of slots for radiating wave energy patterns in response to wave energy excitations and having selected slot orientations and locations which cause wave energy supplied to one end of said waveguide to develop a composite wave energy excitation on said aperture wherein the wave energy supplied to each of said slots has a relative phase and amplitude comprising the vector sum of a plurality of component aperture excitations, measured at the location of said slot in said array, including a reference component excitation and other component excitations having both positive and negative phase variation along said linear array with respect to said reference excitation, said component excitations with positive phase variation having with respect to said reference excitation an average phase displacement which is a first monotonic function of said phase variation, and said component excitations with negative phase variation having with respect to said reference excitation an average phase displacement which is a second monotonic function of said phase variation, all excitations having the same sense of Average phase displacement, thereby resulting in a composite wave energy excitation without substantial amplitude reinforcement of said component excitations at any of said slots in said waveguide.
 5. An antenna system for radiating wave energy signals in a desired radiation pattern, comprising a waveguide having an aperture comprising a linear array of slots formed into one of the narrow walls of said waveguide for radiating wave energy patterns in response to wave energy excitation and having selected slot orientations and locations which cause wave energy supplied to one end of said waveguide to develop a composite wave energy excitation on said aperture wherein the wave energy supplied each of said slots has a relative phase and amplitude comprising the vector sum of a plurality of component aperture excitations, measured at the location of said slot in said array, including a reference component excitation and other component excitations having both positive and negative phase variations along said linear array with respect to said reference excitation, said component excitations with positive phase variation having with respect to said reference excitation an average phase displacement which is a first monotonic function of said phase variation, and said component excitations with negative phase variation having with respect to said reference excitation an average phase displacement which is a second monotonic function of said phase variation, all excitations having the same sense of average phase displacement, thereby resulting in a composite wave energy excitation without substantial amplitude reinforcement of said component excitations at any of said slots in said waveguide.
 6. An antenna system for radiating wave energy signals in a desired radiation pattern, comprising a waveguide having an aperature comprising a linear array of slots for radiating wave energy patterns in response to wave energy excitations and having selected slot orientations and locations which cause wave energy supplied to one end of said waveguide to develop a composite wave energy excitation on said aperature wherein the wave energy supplied each of said slots has a relative phase and amplitude comprising the vector sum of a plurality of uniform amplitude, orthogonalphase component aperature excitations, measured at the location of said slot in said array, including a reference component excitation and other component excitations having both positive and negative phase variation along said linear array with respect to said reference excitation, said component excitations with positive phase variation having with respect to said reference excitation an average phase displacement which is a first monotonic function of said phase variation, and said component excitations with negative phase variation having with respect to said reference excitation an average phase displacement which is a second monotonic function of said phase variation, all excitations having the same sense of average phase displacement, thereby resulting in a composite wave energy excitation without substantial amplitude reinforcement of said component excitations at any of said slots in said waveguide.
 7. An antenna system for radiating wave energy in a desired radiation pattern, comprising a rectangular waveguide, having an aperture comprising a linear array of slots for radiating wave energy patterns in response to wave energy excitations, said slots being formed into one of the narrow walls of said waveguide and having selected slot orientations and locations which cause wave energy supplied to one end of said waveguide to develop a composite wave energy excitation on said aperture wherein the wave energy supplied to each of said slots has a relative phase and amplitude comprising the vector sum of a plurality of uniform-amplitude, orthogonal-phase component aperture excitations, if measured at the location of said slot in said array, including a reference component excitation and other component excitations havIng both positive and negative phase variation along said linear array with respect to said reference excitation, said component excitations with positive phase variation having with respect to said reference excitation an average phase displacement which is a first monotonic function of said phase variation, and said component excitations with negative phase variation having with respect to said reference excitation an average phase displacement which is a second monotonic function of said phase variation, all excitations having the same sense of average phase displacement; thereby resulting in a composite wave energy excitation without substantial amplitude reinforcement of said component excitations at any of said slots in said waveguide. 